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Wang C, Yu J, Kallen CB. Two estrogen response element sequences near the PCNA gene are not responsible for its estrogen-enhanced expression in MCF7 cells. PLoS One 2008; 3:e3523. [PMID: 18949048 PMCID: PMC2568806 DOI: 10.1371/journal.pone.0003523] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 10/06/2008] [Indexed: 12/15/2022] Open
Abstract
Background The proliferating cell nuclear antigen (PCNA) is an essential component of DNA replication, cell cycle regulation, and epigenetic inheritance. High expression of PCNA is associated with poor prognosis in patients with breast cancer. The 5′-region of the PCNA gene contains two computationally-detected estrogen response element (ERE) sequences, one of which is evolutionarily conserved. Both of these sequences are of undocumented cis-regulatory function. We recently demonstrated that estradiol (E2) enhances PCNA mRNA expression in MCF7 breast cancer cells. MCF7 cells proliferate in response to E2. Methodology/Principal Findings Here, we demonstrate that E2 rapidly enhanced PCNA mRNA and protein expression in a process that requires ERα as well as de novo protein synthesis. One of the two upstream ERE sequences was specifically bound by ERα-containing protein complexes, in vitro, in gel shift analysis. Yet, each ERE sequence, when cloned as a single copy, or when engineered as two tandem copies of the ERE-containing sequence, was not capable of activating a luciferase reporter construct in response to E2. In MCF7 cells, neither ERE-containing genomic region demonstrated E2-dependent recruitment of ERα by sensitive ChIP-PCR assays. Conclusion/Significance We conclude that E2 enhances PCNA gene expression by an indirect process and that computational detection of EREs, even when evolutionarily conserved and when near E2-responsive genes, requires biochemical validation.
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Affiliation(s)
- Cheng Wang
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Jie Yu
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Caleb B. Kallen
- Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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2
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Xu J, Morris GF. p53-mediated regulation of proliferating cell nuclear antigen expression in cells exposed to ionizing radiation. Mol Cell Biol 1999; 19:12-20. [PMID: 9858527 PMCID: PMC83861 DOI: 10.1128/mcb.19.1.12] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/1998] [Accepted: 09/18/1998] [Indexed: 11/20/2022] Open
Abstract
The proliferating cell nuclear antigen (PCNA) is a highly conserved cellular protein that functions both in DNA replication and in DNA repair. Exposure of a rat embryo fibroblast cell line (CREF cells) to gamma radiation induced simultaneous expression of PCNA with the p53 tumor suppressor protein and the cyclin-dependent kinase inhibitor p21(WAF1/Cip1). PCNA mRNA levels transiently increased in serum-starved cells exposed to ionizing radiation, an observation suggesting that the radiation-associated increase in PCNA expression could be dissociated from cell cycle progression. Irradiation of CREF cells activated a transiently expressed PCNA promoter chloramphenicol acetyltransferase construct through p53 binding sequences via a mechanism blocked by a dominant negative mutant p53. Electrophoretic mobility shift assays with nuclear extracts prepared from irradiated CREF cells produced four p53-specific DNA-protein complexes with the PCNA p53 binding site. Addition of monoclonal antibody PAb421 (p53-specific) or AC238 (specific to the transcriptional coactivator p300/CREB binding protein) to the mobility shift assay distinguished different forms of p53 that changed in relative abundance with time after irradiation. These findings suggest a complex cellular response to DNA damage in which p53 transiently activates expression of PCNA for the purpose of limited DNA repair. In a population of nongrowing cells with diminished PCNA levels, this pathway may be crucial to survival following DNA damage.
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Affiliation(s)
- J Xu
- Programs in Molecular and Cellular Biology and Lung Biology, Department of Pathology, Tulane Cancer Center and Tulane/Xavier Center for Bioenvironmental Research, New Orleans, Louisiana 70112, USA
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3
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Veal E, Eisenstein M, Tseng ZH, Gill G. A cellular repressor of E1A-stimulated genes that inhibits activation by E2F. Mol Cell Biol 1998; 18:5032-41. [PMID: 9710587 PMCID: PMC109088 DOI: 10.1128/mcb.18.9.5032] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The adenovirus E1A protein both activates and represses gene expression to promote cellular proliferation and inhibit differentiation. Here we report the identification and characterization of a cellular protein that antagonizes transcriptional activation and cellular transformation by E1A. This protein, termed CREG for cellular repressor of E1A-stimulated genes, shares limited sequence similarity with E1A and binds both the general transcription factor TBP and the tumor suppressor pRb in vitro. In transfection assays, CREG represses transcription and antagonizes 12SE1A-mediated activation of both the adenovirus E2 and cellular hsp70 promoters. CREG also antagonizes E1A-mediated transformation, as expression of CREG reduces the efficiency with which E1A and the oncogene ras cooperate to transform primary cells. Binding sites for E2F, a key transcriptional regulator of cell cycle progression, were found to be required for repression of the adenovirus E2 promoter by CREG, and CREG was shown to inhibit activation by E2F. Since both the adenovirus E1A protein and transcriptional activation by E2F function to promote cellular proliferation, the results presented here suggest that CREG activity may contribute to the transcriptional control of cell growth and differentiation.
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Affiliation(s)
- E Veal
- Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA
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4
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Lee BH, Liu M, Mathews MB. Regulation of the human proliferating cell nuclear antigen promoter by the adenovirus E1A-associated protein p107. J Virol 1998; 72:1138-45. [PMID: 9445010 PMCID: PMC124588 DOI: 10.1128/jvi.72.2.1138-1145.1998] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The adenovirus E1A 243R oncoprotein is capable of transactivating the expression of the human proliferating cell nuclear antigen (PCNA) promoter. Mutational analysis of the E1A 243R protein suggested that both its p300/CBP- and p107-binding regions are required for optimal induction of the PCNA promoter (C. Kannabiran, G. F. Morris, C. Labrie, and M. B. Mathews, J. Virol. 67:425-437, 1993). We show that overexpression of p107 antagonizes the induction of PCNA by E1A 243R in transient expression assays. This inhibition is largely independent of p107's ability to interact with E1A 243R, because p107 mutants unable to bind to E1A 243R retain the ability to repress the E1A-activated PCNA promoter. Electrophoretic mobility shift assays with the PCNA promoter detected the presence of p107 in one of the major DNA-protein complexes, EH1, formed with HeLa cell nuclear extracts. Promoter mutations that disrupt the formation of complex EH1 abrogated p107's ability to reverse E1A 243R-induced PCNA expression. The same mutations characterize a sequence important for the binding of transcription factor RFX1 (C. Labrie, G. F. Morris, and M. B. Mathews, Nucleic Acids Res. 23:3732-3741, 1995), implying that p107 antagonizes E1A 243R-induced PCNA expression through this RFX1-binding site. Our data are suggestive of a novel cooperative mechanism for transactivation of PCNA expression, in which E1A 243R relieves transcriptional repression exerted by p107 on the promoter.
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Affiliation(s)
- B H Lee
- Cold Spring Harbor Laboratory, New York 11724-2208, USA
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5
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Lee BH, Mathews MB. Transcriptional coactivator cAMP response element binding protein mediates induction of the human proliferating cell nuclear antigen promoter by the adenovirus E1A oncoprotein. Proc Natl Acad Sci U S A 1997; 94:4481-6. [PMID: 9114015 PMCID: PMC20748 DOI: 10.1073/pnas.94.9.4481] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/1996] [Accepted: 02/28/1997] [Indexed: 02/04/2023] Open
Abstract
The proliferating cell nuclear antigen (PCNA), a crucial component of eukaryotic cell cycle and DNA replication complexes, is induced by the adenovirus E1A 243R oncoprotein through a cis-acting element termed the PERE (PCNA-E1A responsive element). The PERE contains a sequence homologous to an activating transcription factor (ATF) motif, and ATF-1 is a major component of PERE-protein complexes. We have identified a second PERE-binding protein, the cAMP response element binding protein (CREB) transcription factor, which forms heterodimers with ATF-1 at this site. CREB, but not ATF-1, is able to mediate transactivation of a minimal PCNA-chloramphenicol acetyltransferase reporter by E1A 243R. Further analysis revealed that the transcriptional coactivator, the CREB-binding protein (CBP), associates with PERE-related complexes, and that CBP is able to mediate a strong transactivation response to E1A 243R at the PCNA promoter. Experiments conducted with mutants in the E1A or CREB components support a model whereby E1A 243R transactivates the PCNA promoter via a CBP-CREB-PERE pathway. These findings delineate a paradigm by which E1A 243R can target and transactivate specific DNA promoter sequences.
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Affiliation(s)
- B H Lee
- Department of Molecular Genetics and Microbiology, State University of New York at Stony Brook, Stony Brook, NY 11790, USA
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6
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Ressler S, Morris GF, Marriott SJ. Human T-cell leukemia virus type 1 Tax transactivates the human proliferating cell nuclear antigen promoter. J Virol 1997; 71:1181-90. [PMID: 8995640 PMCID: PMC191171 DOI: 10.1128/jvi.71.2.1181-1190.1997] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The human T-cell leukemia virus type 1 (HTLV-1) transforming protein, Tax, is a potent transactivator of both viral and cellular gene expression. The ability of Tax to transform cells is believed to depend on its transactivation of cellular-growth-regulatory genes. Expression of proliferating cell nuclear antigen (PCNA) is intimately linked to cell growth and DNA replication and repair. By testing a series of PCNA promoter deletion constructs, we have demonstrated that the PCNA promoter can be transactivated by Tax. The smallest construct that was activated did not include the ATF/CRE binding site at nucleotide -50, and mutations in the ATF/CRE element in the context of a larger promoter were still activated by Tax. In addition, a Tax mutant that is defective for activation of the CRE pathway retained the ability to activate the -397 promoter construct. When a series of linker scanner mutations that span the region from nucleotide -45 to -7 were assayed, mutations in and around a repeat sequence were found to abolish Tax transactivation. Multimerized copies of either half of the repeat were Tax responsive. A single protein complex was shown to bind specifically to the Tax-responsive region, and the binding of this complex was enhanced in the presence of Tax. These results demonstrate that the PCNA promoter contains a Tax-responsive element located between nucleotides -45 and -7 whose sequence is different from those of other, previously identified Tax-responsive elements. The ability of Tax to activate the PCNA promoter may play an important role in cellular transformation by HTLV-1.
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Affiliation(s)
- S Ressler
- Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA
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7
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Sollerbrant K, Chinnadurai G, Svensson C. The CtBP binding domain in the adenovirus E1A protein controls CR1-dependent transactivation. Nucleic Acids Res 1996; 24:2578-84. [PMID: 8692699 PMCID: PMC145971 DOI: 10.1093/nar/24.13.2578] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The adenovirus E1A-243R protein has the ability to force a resting cell into uncontrolled proliferation by modulating the activity of key targets in cell cycle control. Most of these regulatory mechanisms are dependent on activities mapping to conserved region 1 (CR1) and the non-conserved N-terminal region of E1A. We have previously shown that CR1 functions as a very patent transactivator when it is tethered to a promoter through a heterologous DNA binding domain. However, artificial DNA binding was not sufficient to convert full-length E1A-243R to a transactivator. Thus, an additional function(s) of the E1A-243R protein modulates the effect of CR1 in transcription regulation. Here we demonstrate that a 44 amino acid region at the extreme C-terminus of ElA inhibited transactivation by a Gal4-CR1 fusion protein. Inhibition correlated with binding of the nuclear 48 kDa C-terminal binding protein (CtBP), which has been implicated in E1A-mediated suppression of the metastazing potential of tumour cells. This might suggest that CtBP binding can regulate E1A-mediated transformation by modulating CR1-dependent control of transcription.
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Affiliation(s)
- K Sollerbrant
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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8
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Morris GF, Bischoff JR, Mathews MB. Transcriptional activation of the human proliferating-cell nuclear antigen promoter by p53. Proc Natl Acad Sci U S A 1996; 93:895-9. [PMID: 8570655 PMCID: PMC40154 DOI: 10.1073/pnas.93.2.895] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Proliferating-cell nuclear antigen (PCNA) is a DNA damage-inducible protein that performs an essential function in DNA replication and repair as an auxiliary factor for DNA polymerases delta and epsilon. Examination of the human PCNA promoter DNA sequence revealed a site with homology to the consensus DNA sequence bound by p53. PCNA promoter fragments with this site intact bound p53 in vitro and were transcriptionally activated by wild-type p53 in transient expression assays in SAOS-2 cells. The resident p53-binding site could be functionally substituted by a previously described p53-binding site from the ribosomal gene cluster. A plasmid expressing a mutated version of p53 derived from a patient with Li-Fraumeni syndrome failed to activate the PCNA promoter in the cotransfection assay. In different cell types, activation of the PCNA promoter by the p53-binding sequence correlated with the status of p53. Activation of the PCNA promoter by wild-type p53 depends upon the level of p53 expression. This concentration dependence and cell type specificity reconciles the observations presented here with prior results indicating that wild-type p53 represses the PCNA promoter. These findings provide a mechanism whereby p53 modulates activation of PCNA expression as a cellular response to DNA damage.
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Affiliation(s)
- G F Morris
- Cold Spring Harbor Laboratory, NY 11724, USA
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9
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Labrie C, Lee BH, Mathews MB. Transcription factors RFX1/EF-C and ATF-1 associate with the adenovirus E1A-responsive element of the human proliferating cell nuclear antigen promoter. Nucleic Acids Res 1995; 23:3732-41. [PMID: 7479004 PMCID: PMC307273 DOI: 10.1093/nar/23.18.3732] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The proliferating cell nuclear antigen (PCNA) is an adenovirus E1A-inducible factor that is intimately linked to the processes of DNA replication and cell cycle regulation. Previously, we defined a novel cis-acting element, the PCNA E1A-responsive element (PERE), that confers induction by the E1A 243R oncoprotein upon the human PCNA promoter. To better understand the regulation of PCNA expression by E1A 243R, we have identified cellular transcription factors that associate with the PERE. In electrophoretic mobility shift assays, the PERE formed three major complexes (P1, P2 and P3) with proteins in nuclear extracts from HeLa or 293 cells. Formation of complexes P2 and P3, which correlates with PCNA promoter activity in vivo, requires the activating transcription factor (ATF) binding site found within the PERE [Labrie et al. (1993) Mol. Cell. Biol., 13, 1697-1707]. Antibody interference experiments and mobility shift assays performed with in vitro-synthesized protein indicated that the transcription factor ATF-1 is a major component of these complexes. Similar assays demonstrated that the hepatitis B virus enhancer-associated protein RFX1 constitutes a major component of the P1 complex. In addition, we examined the binding of proteins to the minimal E1A-responsive promoter to identify other factors important for transcription from the PCNA promoter. Mobility shift assays revealed that a fragment encompassing the region from -87 to +62 relative to the transcription initiation site forms at least five complexes, EH1-EH5, with HeLa cell nuclear extracts. The transcription factor YY1 associates with the initiator element of the PCNA promoter. The identification of these transcription factors will allow their roles in the activation of PCNA by E1A to be evaluated.
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Affiliation(s)
- C Labrie
- Cold Spring Harbor Laboratory, NY 11724-2208, USA
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10
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Bondesson M, Mannervik M, Akusjärvi G, Svensson C. An adenovirus E1A transcriptional repressor domain functions as an activator when tethered to a promoter. Nucleic Acids Res 1994; 22:3053-60. [PMID: 8065919 PMCID: PMC310275 DOI: 10.1093/nar/22.15.3053] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The adenovirus E1A protein contains three well conserved regions, designated conserved region (CR) 1, 2 and 3, which are important for the multiple activities ascribed to E1A. The CR3 domain constitutes a prototypic transcription activator, consisting of a promoter targeting region and a transactivating region. Here we demonstrate the existence of a second transactivating region located within amino acids 28 to 90 (essentially the CR1 domain) of the E1A protein. A fusion protein, containing the Gal4 DNA binding domain linked to CR1, was as efficient as the classical CR3 transactivator in activating transcription from a reporter plasmid containing Gal4 binding sites. However, competition experiments suggest that Gal/CR1 and Gal/CR3 work through different cellular targets. The E1A-243R protein has previously been extensively characterized as a repressor of transcription. Here we show that a Gal4 fusion protein expressing the CR1 domain is indeed sufficient for repression of SV40 enhancer activity. Collectively, our results suggest that CR1 functions as an activator if tethered to a promoter and as a repressor in the absence of promoter association.
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Affiliation(s)
- M Bondesson
- Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden
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11
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Promoter activity of the proliferating-cell nuclear antigen gene is associated with inducible CRE-binding proteins in interleukin 2-stimulated T lymphocytes. Mol Cell Biol 1994. [PMID: 7910946 DOI: 10.1128/mcb.14.6.4233] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The proliferating-cell nuclear antigen (PCNA) gene encodes an auxiliary factor of DNA polymerase delta and functions in DNA replication during S phase. It is expressed at much higher levels in proliferating cells than in quiescent cells. We have studied the regulatory role of the 5'-flanking sequence of the murine PCNA gene in interleukin 2 (IL-2)-responsive cloned T cells (L2). Analysis of a set of deletion constructs in transient transfection assays measuring heterologous reporter gene (luciferase) activity demonstrated that the 182-bp 5'-flanking region provides full promoter activity in IL-2-stimulated L2 cells. While many elements contribute to PCNA promoter strength in IL-2-stimulated cells, the largest decrease in activity occurred with deletion of the tandem CRE (cyclic AMP response element) binding sites located at nucleotides -37 to -52. With a gel mobility shift assay, several IL-2-inducible DNA-protein complexes were detected, including CREB (CRE-binding) and ATF1 (activating transcription factor) proteins that are specific for the PCNA-CRE sequence. Methylation interference analysis confirmed specific binding of these proteins to the CRE sites. Mutation at the PCNA-CRE motif abolishes IL-2-inducible binding and reduces substantially PCNA promoter activity. These results indicate that IL-2-stimulated PCNA transcription may be partially mediated by these CRE-binding proteins.
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12
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Huang D, Shipman-Appasamy PM, Orten DJ, Hinrichs SH, Prystowsky MB. Promoter activity of the proliferating-cell nuclear antigen gene is associated with inducible CRE-binding proteins in interleukin 2-stimulated T lymphocytes. Mol Cell Biol 1994; 14:4233-43. [PMID: 7910946 PMCID: PMC358789 DOI: 10.1128/mcb.14.6.4233-4243.1994] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The proliferating-cell nuclear antigen (PCNA) gene encodes an auxiliary factor of DNA polymerase delta and functions in DNA replication during S phase. It is expressed at much higher levels in proliferating cells than in quiescent cells. We have studied the regulatory role of the 5'-flanking sequence of the murine PCNA gene in interleukin 2 (IL-2)-responsive cloned T cells (L2). Analysis of a set of deletion constructs in transient transfection assays measuring heterologous reporter gene (luciferase) activity demonstrated that the 182-bp 5'-flanking region provides full promoter activity in IL-2-stimulated L2 cells. While many elements contribute to PCNA promoter strength in IL-2-stimulated cells, the largest decrease in activity occurred with deletion of the tandem CRE (cyclic AMP response element) binding sites located at nucleotides -37 to -52. With a gel mobility shift assay, several IL-2-inducible DNA-protein complexes were detected, including CREB (CRE-binding) and ATF1 (activating transcription factor) proteins that are specific for the PCNA-CRE sequence. Methylation interference analysis confirmed specific binding of these proteins to the CRE sites. Mutation at the PCNA-CRE motif abolishes IL-2-inducible binding and reduces substantially PCNA promoter activity. These results indicate that IL-2-stimulated PCNA transcription may be partially mediated by these CRE-binding proteins.
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Affiliation(s)
- D Huang
- Department of Pathology, School of Medicine, University of Pennsylvania, Philadelphia 19104
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13
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Modulation of transcriptional activation of the proliferating cell nuclear antigen promoter by the adenovirus E1A 243-residue oncoprotein depends on proximal activators. Mol Cell Biol 1994. [PMID: 7903420 DOI: 10.1128/mcb.14.1.543] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous analyses defined a proliferating cell nuclear antigen (PCNA) E1A-responsive element (PERE) in the PCNA promoter that is essential for transactivation by the 243-residue product of the adenovirus type 2 E1A 12S mRNA (E1A 243R). In this report, we show that the PERE activates a heterologous basal promoter and confers susceptibility to transactivation by E1A 243R, indicating that the PERE is both necessary and sufficient for the response of the PCNA promoter to this oncoprotein. Insertion of linker sequences between the PERE and the site of transcription initiation in the PCNA promoter severely impairs the promoter's response to E1A 243R transactivation. GAL4 sites can replace the function of the PERE in the E1A 243R response of the PCNA basal promoter if transcriptional activators of suitable strength are supplied as GAL4 fusion proteins. Weak transcriptional activators render the PCNA basal promoter subject to transactivation by E1A 243R but do not endow the adenovirus E1B basal promoter with a similar response. Strong transcriptional activators do not support transactivation by E1A 243R, however; instead, E1A reduces the ability of the strong activators to activate both the PCNA and E1B basal promoters. Although other mechanistic differences might determine the response, the data imply a relationship between the activation strength of promoter-proximal effectors and the response of the PCNA basal promoter to E1A 243R. These experiments indicate that the PERE can function autonomously in mediating transactivation by E1A 243R and that the PCNA basal promoter is configured in a manner that permits modulation by E1A 243R of transcriptional activation by promoter-proximal effectors.
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14
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Morris GF, Labrie C, Mathews MB. Modulation of transcriptional activation of the proliferating cell nuclear antigen promoter by the adenovirus E1A 243-residue oncoprotein depends on proximal activators. Mol Cell Biol 1994; 14:543-53. [PMID: 7903420 PMCID: PMC358404 DOI: 10.1128/mcb.14.1.543-553.1994] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Previous analyses defined a proliferating cell nuclear antigen (PCNA) E1A-responsive element (PERE) in the PCNA promoter that is essential for transactivation by the 243-residue product of the adenovirus type 2 E1A 12S mRNA (E1A 243R). In this report, we show that the PERE activates a heterologous basal promoter and confers susceptibility to transactivation by E1A 243R, indicating that the PERE is both necessary and sufficient for the response of the PCNA promoter to this oncoprotein. Insertion of linker sequences between the PERE and the site of transcription initiation in the PCNA promoter severely impairs the promoter's response to E1A 243R transactivation. GAL4 sites can replace the function of the PERE in the E1A 243R response of the PCNA basal promoter if transcriptional activators of suitable strength are supplied as GAL4 fusion proteins. Weak transcriptional activators render the PCNA basal promoter subject to transactivation by E1A 243R but do not endow the adenovirus E1B basal promoter with a similar response. Strong transcriptional activators do not support transactivation by E1A 243R, however; instead, E1A reduces the ability of the strong activators to activate both the PCNA and E1B basal promoters. Although other mechanistic differences might determine the response, the data imply a relationship between the activation strength of promoter-proximal effectors and the response of the PCNA basal promoter to E1A 243R. These experiments indicate that the PERE can function autonomously in mediating transactivation by E1A 243R and that the PCNA basal promoter is configured in a manner that permits modulation by E1A 243R of transcriptional activation by promoter-proximal effectors.
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Affiliation(s)
- G F Morris
- Cold Spring Harbor Laboratory, New York 11724
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